Often, there is a desire to introduce a new network element into an existing network such as 3GPP network. This desire could be driven by many diverse requirements, such as improving network performance, monitoring network conditions, improvement of user experience, improving security aspects of the network or the user or for any of the myriad of things that are possible. Such a device may need to be placed logically as a “bump in the wire” in the network, in the sense that it is placed between two devices and both devices are unaware of the newly introduced device. Such a placement of the new device could be either physically in-line between the two devices or logically in-line, such that the traffic is routed through the new device.
Protocol standards define one or more layers of control protocol interactions between two devices over a connected interface. These control protocol operations define actions to be performed by each device while interacting with an adjacent device, or neighbor for managing user data-plane sessions. Examples of such operations include establishing, modifying, and terminating a user data plane session, such as Packet Data Protocol (PDP) context, or creating, modifying, and terminating a Radio Access Bearer (RAB) for active PDP context in 3GPP/UMTS mobile network. When a “bump in the wire” type device, as described above, is placed between two standards-defined communication devices, this new device will be operating outside the scope of the corresponding control protocol standards. Thus, the new device does not have any identity in the respective protocol framework. The interfaces shown (IuB, IuPS etc.) in the accompanying figures are logical protocol interfaces and may be transported through ATM or IP transports per 3GPP/UMTS standards. The interface protocol standards define both the control protocols for managing user sessions through the mobile network, as well as the user plane packet encapsulation protocols. The focus of the current invention is control plane protocols on these interfaces.
FIG. 1 exemplifies the placement of a “bump in the wire” device per the current invention on the IuPS interface in a 3G/UMTS network 1. FIG. 1a shows a traditional UTMS Radio access network. A Serving GPRS Support Node (SGSN) 4 is responsible for the delivery of data packets from and to the mobile stations within its geographical service area. The Radio Network Controller (or RNC) 5 is a governing element in the radio access network and is responsible for controlling the NodeBs 6 that are connected to it. NodeB 6 is a term used to denote the base transceiver station (BTS) in the UMTS/3GPP Architecture. One or more RNCs at different locations are connected to one or more SGSNs through an ATM or IP transport network. This example shows RNC 5 connected to SGSN 4 through ATM-Switch 7 using the IuPS logical interface; this means both RNC and SGSN are connected to an ATM Switch, one or more ATM-VCs are configured through the ATM-Switch 7, and IuPS protocols are carried through the ATM-VCs.
FIG. 1b represents the placement of the new device 9 physically inline within the network shown in FIG. 1a. In this embodiment, the new device 9 is logically placed between the SGSN 4 and the RNC 5 through the ATM-Switch 8, and utilizes the IuPS protocol on both of its interfaces. In other words, it appears as the RNC 5 to the SGSN 4 and as the SGSN 4 to the RNC 5 on the IuPS logical interface. FIG. 1c shows the new device placement logically inline between the RNC 5 and SGSN 4 through the ATM-Switch; i.e., the ATM Switch is configured to terminate the IuPS ATM-VCs from the RNC 5 and the SGSN 4 in the new device 9, and the new device performs the operations identified in the current invention.
Many types of bridges exist. For example, protocol bridges, such as Layer 2 Ethernet bridges (IEEE 802.1D, 802.1Q), operate by intercepting Ethernet Layer 2 MAC Header, and using these headers to build internal forwarding tables to associate Layer 2 MAC Addresses with 1 or more forwarding ports within the Bridge. The goals of such a bridge are to extend the interconnectivity between the connected devices (i.e. the number of nodes that can participate in the Layer 2 network), extend the network reach beyond the Ethernet Physical Layer, and increase the total Bandwidth among a number of nodes by providing simultaneous packet transfer operations. These Layer 2 bridges forward packets received from one interface to one or more interfaces based on their Layer 2 Header without modifying the packet contents.
Layer 3 forwarding devices, such as IP routers, intercept packets from one or more interfaces, and forward them to one or more interfaces. Depending on the type of lower layer transport they are connected to, these devices may modify the Layer 2 headers. The goal of such devices is to extend the Network Connectivity at Layer 3 among a number of devices, and increase the Bandwidth among a large number of devices.
Repeaters, such as Ethernet Repeaters, extend the physical reachability of the two devices that they connect to (i.e. the distance between devices is increased). They terminate or extend the corresponding link layer protocols and forward upper layer packets from one interface to another.
Each of these prior art devices simply forwards existing packets to one or more destinations. In some embodiments, the device modifies the packet, typically at the Layer 2 or Layer 3 level to expand the network. However, it may be desirable and advantageous to introduce new messages into the network, or to terminate other flows.